Amateur astronomers are filled with anticipation: two planetary events that haven’t occurred in a while will take place in May 2016. Mercury will pass in front of the Sun on the 9th, and Mars will arrive at opposition on the 22nd, passing closest to Earth at month’s end.
Transit of Mercury
Circle May 9 on your calendar without delay: On that day, Mercury will cut across the Sun’s disk from one side to the other. This somewhat rare event takes place about every eight years on average, and for the first time since 1960, it will be visible, in its entirety, from Quebec!
From Montreal, Mercury will first contact the edge of the Sun’s disk at 7:13:27 a.m., Eastern Daylight Time (the precise moment of contact will vary by a few seconds, plus or minus, depending on your distance from the city). Starting at 7:16:39 (second contact), Mercury will be completely silhouetted against the Sun, which will appear well up above the eastern horizon. Throughout the morning, the tiny planet will pursue its course across the solar face: at 10:57:47 Mercury will be half-way across the Sun which will, by then, be 54 degrees above the eastern horizon.
The planet’s egress, which marks the end of the event, will take place from 14:38:08 (third contact) to 14:41:19 (fourth contact). At that point, the Sun will be high up in the southwest. In all, this transit of Mercury will last almost 7 hours and a half. The time span will prove an advantage if weather conditions are less than ideal.
Because Mercury’s diameter is 160 times smaller than the Sun’s, the tiny planet can only be observed through a properly filtered telescope. It is dangerous to look directly at the Sun with the naked eye, and much more so through a system of magnifying optics. To safely follow Mercury’s transit, it’s essential to use specialized solar filters; barring that, you can view a projected image. Though Mercury will cross the Sun again on November 11, 2019, the next transit after that won’t occur until November 13, 2032 — and it won’t be visible from Quebec! So let’s hope for blue skies this May 9.
Opposition of Mars
At long last, Mars finally arrives at opposition on May 22… and it’s best one in over 10 years! For several weeks, the Red Planet will remain visible from sunset to sunrise as it moves westward among the stars of Ophiuchus, Scorpius and Libra. This is also the period when Mars will be closest to Earth, and brightest. At opposition, the planet’s distance can vary from 56 million to 100 million kilometers: This time around, during its closest approach on May 30, Mars will be only 75 million kilometers away.
Seen through a telescope, Mars offers a variety of visual characteristics: white polar ice caps, orange desserts, and dark regions covered in volcanic dust. But to really appreciate Mars, one should observe it when it is highest above the horizon, which is around midnight this May. Though the northern polar cap will be tilted toward Earth, its size will likely be reduced because the opposition of 2016 coincides with mid-summer in the Martian northern hemisphere.
A colourful vista is in store for naked eye observers on the evening and night of May 21 to 22. Around 10 p.m., in the southeast, the full moon will form a celestial rectangle along with Mars, Saturn, and the star, Antares, in Scorpius.
Oppositions of Mars occur about every 26 months, and the next one, in July 2018, promises to be even more spectacular: The Red Planet will be just 56 million kilometers away from Earth! So think of this month’s opposition as an excellent prelude.
Jupiter and Saturn
Let’s not overlook twilight’s feature attraction, Jupiter, which shines brightly to the left of Regulus, in the constellation of Leo, the Lion. Throughout the month, Jupiter will be visible from sunset until about 2:00 in the morning. On the evening of May 14, look for the gibbous moon to accompany the giant planet.
Saturn is currently located just a few degrees to the left of Mars. Don’t hesitate to train your telescope on this magnificent object: Saturn’s rings are tilted 26 degrees toward Earth, providing a truly spectacular sight. The nearly-full moon will appear near the ringed planet on the evening of May 22.
In closing, amateur photographers should watch for a thin lunar crescent, in the west, just after sunset on May 7, 8, and 9. An excellent opportunity for some breathtaking images.
Following the cold nights of winter, before they’re cut short by the summer season, May provides ideal conditions for exploring the starry sky. Why not give it a try?